The present invention relates to joints for use in collapsible chairs and other pieces of indoor or outdoor furniture. More particularly, the invention relates to improvements in joints which can be used with advantage in collapsible chairs to articulately connect the back support to the seat as well as to a ground- or floor-contacting part (foot or leg) of a collapsible chair, cot or the like.
It is already known to provide a joint for use in a collapsible chair or the like with a two-piece main component having a stub which is secured to the seat and has two shells pivotally supporting two levers one of which has a stub connected to the back of the chair and the other of which has a stub connected to the rear foot or leg of the chair. As a rule, the levers are pivotable relative to the main component through angles of between 90 and 120 degrees, namely between first positions in which the chair is collapsed for storage or transport and second positions in which the chair is erected and is ready for use. In many instances, the stub of the main component is parallel to the stubs of the two levers in the collapsed position of the chair. The shells of the two-piece main component define a housing for a transmission which couples the levers to each other so that any angular movement of one lever relative to the main component necessarily entails a predetermined angular movement of the other lever with reference to the main component and vice versa.
German Pat. No. 23 49 264 discloses a joint wherein the transmission which is interposed between the two levers comprises a rather bulky gear train having several disc-shaped mating gears. Since the shaping of cut, rolled, ground or similarly machined and finished gears in a manner as is customary in the machine industry would be too expensive for use in the joint of a rather simple collapsible chair or a like low-priced piece of furniture, the disc-shaped gears are simple stampings or similar inexpensive mass-produced parts whose teeth mate with a substantial amount of play. This results in the development of excessive localized stresses and can entail rapid destruction of the joint. Moreover, the teeth of the disc-shaped gears are likely to gather dust and other contaminants.
German Utility Model No. 19 52 927 discloses a joint for use in a three-legged bed. The main component of the joint is articulately connected to the frame of the bed by a link which provides sufficient room for movement of pivotable parts of the collapsible bed between their extended and collapsed positions.
German Auslegeschrift No. 12 53 961 discloses a rather complex joint for a cot, a deck chair or a similar piece of furniture. This joint is designed to allow for movements of the back support to any one of several different positions of inclination with reference to the seat. The drawbacks of this joint are its bulk, complexity (large number of parts), substantial cost and proneness to contamination.